ive never NOT sealed off the walls ive build
seems stupid not to. and i consider it a must.
few people who didnt seal off at first and then did say they increased the low end output
most increase in pressure considering your making the cabin smaller
deff google it tons of builds and people opinions on it im sure youll find even meter proof it helps in the numbers game
not everyone shit is the same and shit...so...yeah dont take one persons opinion on it. cuz facts and things and stuff